A blocked pest caller is able to leave computer generated messages.  My Galaxy 4 doesn't ring, there's no record in the recent call list, but I get a notification about a new voicemail.  This fake voice warns of actions against me by the "local cops", and implores me to call immediately.  There were two of these just today (16 Mar 2018).  If the number this call came from is blocked why are these voicemails getting through?  Seems like my service provder isn't doing enough to protect it's customers from this vile scum.  I can find no help with this on your web support pages.